Fig. 4
The foliar δ15N values of the Brassica napus plantlets cultured under nitrate treatment. Note: (a) The foliar δ15N values of the Brassica napus plantlets in the L-labeled treatment. (b) The foliar δ.15 N values of the Brassica napus plantlets in the H-labeled treatment. Each nitrate treatment contained 20 mM ammonium. The mean ± SE (n = 3) followed by different letters in the same legend differ significantly (Tukey’s test, p < 0.05)